For years, scientists believed that a person’s handedness – whether they prefer to use their left or right hand – was genetic, but it was unknown which genes determined a person’s dexterity, until now.

A new study compiled using research from Oxford, Bristol, Scotland and the Netherlands universities has isolated the network of genes responsible.

They also found that the network establishes the left-right differences in the brain, which in turn influences the favoured hand, while an embryo is developing.

Oxford’s William Brandler said: ‘The genes are involved in the biological process through which an early embryo moves on from being a round ball of cells and becomes a growing organism with an established left and right side.’

Humans are the only species to show such a strong bias in handedness, with around 90 per cent of people being right-handed. But the cause of this bias remains largely a mystery.

The team carried out a genome-wide association study to identify any common gene variants that might correlate with which hand people prefer using.

They found that most strongly associated variant with handedness is located in the gene PCSK6, which is involved in the early establishment of left and right in the growing embryo.

Reviewing earlier studies, they established that in mice, disrupting PCSK6 causes ‘left-right asymmetry’ defects, such as abnormal positioning of organs in the body.

This might mean they have a heart and stomach on the right and their liver on the left, for example.

But Brandler warns that while the genes appear to play a part, they are not the only influencing factor.

He said: ‘As with all aspects of human behaviour, nature and nurture go hand-in-hand.

‘The development of handedness derives from a mixture of genes, environment, and cultural pressure to conform to right-handedness.’